This invention relates to the interconnection of signal lines and power lines among circuit chips such as monolithic microwave integrated circuits (MMICS) and electromechanical circuits supported on a common substrate and, more particularly, to an arrangement of vias passing through the circuit chip and normal to a surface of the substrate permitting the use of multiple bumps for batch processing of connections among components of plural chips such as MMICs in a multiple chip assembly (MCA).
In recent years, advances in the performance and ease of manufacture of gallium arsenide (GaAs) devices, MMICs, and MCAs have resulted in their utilization in numerous military and commercial systems. Essential to the utilization of this technology for construction of an MCA is the ability to form, repetitively and accurately, interconnects to MMIC chips and a common substrate which supports the chips. It has been the practice in the construction of an MCA to form RF (radio frequency) and dc (direct current) interconnects and control lines by wire or ribbon bonds.
A problem arises in that, at microwave and especially at millimeter-wave frequencies, bond wires in MCAs introduce a variable high series reactance and conductor loss. Such a wire bond may serve as a source of radiation and introduce increased electromagnetic coupling among components of the MCAs, with a resultant diminution in isolation among the components and possible occurrence of oscillations in circuits having high-gain blocks. This handicap becomes particularly noticeable with increasing frequency. Such degradation of performance is of particular importance at millimeter-wave frequencies.